A wide variety of computer systems have been used to create, edit, deliver, and store recorded signals, such as, music. Such computer systems generally include commercially-available computer program products which allow people to create music from multiple recorded signals, edit the music in a variety of ways including combining and changing multiple recorded signals, and store the music in some medium that allows the user to deliver the music in some fashion. Examples of such computer program products include ACID, VEGAS, and SIREN software programs developed and sold by Sonic Foundry, Inc., of Madison, Wis. These exemplary programs are described and can be purchased on the Internet at http://www.sonicfoundry.com.
Such computer-readable recorded signals can be stored in a variety of different computer storage formats. While a computer is inherently a digital machine, recorded signals can be stored in a digital form or an analog form, depending on the application and selected file format. A variety of computer file formats can be used to store recorded signals. Example file formats include the Moving Picture Experts Group Layer-3 Audio (MP3) audio file format, MICROSOFT wave (WAV) audio file format, and Windows Media Audio (WMA) audio file format.
Heretofore, much popular music is produced using computers and other electronic devices. Therefore, such music can include rhythms which repeat at very precise intervals. Disc jockeys, for example, count on the precision of such rhythms to synchronize playback and create new mixes of music. Computer systems can be particularly helpful in the synchronization of such music because of the capacity of computers to combine and process audio signals, maintain large libraries of songs, and store such creations for later delivery.
One of the challenges in creating music collages on computer systems is that music is recorded in a wide range of different tempos. Understandably, music that is recorded at one tempo does not sound good when mixed with music recorded at another. Thus, knowing the tempo and downbeat is important in the creation and editing of music. Nevertheless, music recordings on compact discs (CD), tapes, or other media, generally do not include information on tempo in the recorded signal. It is, therefore, difficult (if not impossible) to properly mix musical media with other musical recordings without having tempo information.
Thus, there is a need for a system for and a method of determining the period of recurring events within a recorded signal. Further, there is a need to precisely identify tempo of a recorded signal so that multiple recorded signals can be successfully mixed together. Even further, there is a need to synchronize musical loops and other musical media to any song and to other time based events such as video, animation, lights, or other timing critical devices.
The teachings hereinbelow extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the above-mentioned needs.